1. Field of the Invention
The present invention relates to propulsion devices, and more particularly to a device in which a novel configuration of airfoil elements is provided, in an inclined circular array.
2. Description of the Prior Art
In U.S. Pat. Nos. 5,137,424 and 5,213,474 of the present inventor, the discovery of important fluid dynamic principles has been embodied in various pump designs, to improve the movement of a fluid through a body. Similarly, in the present inventor's U.S. Pat. No. 5,104,541, which issued from a divisional application of the above-mentioned U.S. Pat. No. 5,137,424, the fluid dynamic principles are embodied in an oil-water separator. In the present application, these principles are embodied somewhat differently, to improve the movement of a body through a fluid.
More directly, the present invention constitutes an improvement on and a departure from the VTOL craft described in the present inventor's earlier U.S. Pat. No. 5,102,066. In that patent, a propeller unit comprising a circular series of horizontally-disposed airfoil elements was mounted on a double-shell structure, such that the airfoil elements occupied the annular space defined by the bottoms of the twin shells.
It has now been recognized, however, that the VTOL of the inventor's earlier patent described above has the disadvantage that the vacuum created within the double-shell structure creates not only a lift on the underside of the craft, but also a downward force on the upper surfaces of the double-shell structure, which tends to neutralize the lift.